Study of damage mechanics in continuous-fiber composite laminates with matrix cracking and internal delaminations
Thesis/Dissertation
·
OSTI ID:5309103
A cumulative damage model for predicting the stiffness loss in crossply graphite/epoxy laminates is obtained by applying a thermomechanical constitutive theory for elastic composites with distributed damage. The model proceeds from a continuum mechanics and thermodynamics approach wherein the distributed damage is characterized by a set of second-order tensor-valued internal-state variables. The internal-state variables represent globally averaged measures of matrix cracking and internal delaminations. The resulting model represents a set of damage-dependent laminate-plate equations. These are developed by modifying the classical Kirchhoff plate theory. The effect of internal delamination enters the formulation through modifications of the Kirchhoff displacements. The corresponding internal-state variable is defined, utilizing the kinematics of the internal delaminated region and the divergence theorem. This internal-state variable represents the components of the out-of-plane displacement modes created by the delamination. A local anisotropic stiffness is then defined to couple these out-of-plane displacements with the in-plane forces. The effect of the matrix cracking enters the formulation through alteration in the individual lamina constitution. The internal-state variable is related to the surface area of delamination by employing linear elastic fracture mechanics.
- Research Organization:
- Texas A and M Univ., College Station (USA)
- OSTI ID:
- 5309103
- Country of Publication:
- United States
- Language:
- English
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